Establish Agency System Properties

Establish the essential system-wide characteristics that will guide all design decisions.

	A-TARS: - Agency-Wide System Properties - Strategic Analysis and Data - Changes - Technical Architecture Work Plans and Direction - AIS Design and Implementation Info.
Describe Essential Properties Update Essential Properties		A-TARS: Agency-Wide System Properties - Status
	- Technical Architecture Team

Introduction

The A-TARS describes a set of elementary building blocks that are incorporated into the HS Agency systems. It also describes how the elements are arranged to create applications and automated systems. To provide uniformity across the elements, global properties are established. Properties reflect basic assumptions about the nature of the application system, such as how long it should operate before failure, what constitutes a failure, how much it should cost per user to maintain, how secure is secure enough, and what is the usability.

These properties constrain and influence design choices that architects and designers make when designing all or part of the HS Agency systems. They must incorporate features into the design to address these critical characteristics. As individual descriptions in the A-TARS are produced, they are checked for consistency with these properties.

These activities explicitly recognize the possibility that these properties, once established, will change - it is only a matter of when. As the environments in which the systems change, the essential properties must keep pace. For example, a system built to serve users within the confines of the HS Agency office complex needs different scalability characteristics once it's available to anyone on the World Wide Web. Likewise, the need for security, privacy, and integrity characteristics of the automated systems will change as the systems are moved to the Internet.

TANF Example:

The function and data linking between TANF, Food Stamps, Medicaid, and Children's Health Insurance Program (CHIP) systems affects the way business (eligibility) rules are defined, managed, and executed. Technology design approaches should help isolate and allow for assuring the accuracy and performance of TANF eligibility rules, within the broader context of the other programs. Individual and cross-program rules must be easily and accurately tested. Mechanisms incorporated into the application systems must therefore make sure that rules cannot be inadvertently corrupted. Integrity and accuracy of the shared data requires that rules be separately verified and their interaction understood. These data integrity and accuracy properties will guide the design of the shared data entities and associated rule processing logic.

Top

Activities

Consolidated guidelines are available to perform the following key activities:

Describe Essential Properties. These actions create the initial list of properties. Sources of characteristics can be obtained by:
- Consulting the HS IT Strategic Plan
- Reviewing weaknesses or strengths of existing technology assets compiled during the Scan HS IT Division Environment activities, especially their quality attributes
- Holding discussions with the HS program staff
- Reviewing analysis generated during the Describe Technology Boundaries activities
- Surveying vendor offerings
Properties can be documented in the main body portion of the A-TARS because properties apply across all the design elements. The Chief Architect and other experienced individuals are responsible for identifying and documenting these properties. Because these may be significant technical cost drivers, they should be reviewed by key stakeholders, such as IT Decision Makers, individuals representing the HS Programs, and the IT Project Teams.

Once the properties are in draft form, they can be released to the other members of the Architecture Team to begin their analysis and design activities (see the activities described in the Establish Technical Architecture Reference Set). All portions of the A-TARS are reviewed against the properties to identify issues that may compromise obtaining that property (e.g., an application architecture design that is not easily maintainable).
Update Essential Properties. These actions maintain the property descriptions once they have been released for use within or external to the Architecture Team. Updates may occur after the first draft of the properties is released to the Architecture Team or after formal releases of the A-TARS. When these properties change, the configuration of the Technical Architecture descriptions that depend on them must be identified and evaluated for impact. Deployed systems, applications, or practices that are related to a property must also be evaluated (e.g., security practices). Change actions can be planned for the architectural elements, the deployed systems, and management and engineering practices. This implies a general ability to trace between the property descriptions; the other elements of the A-TARS; and the systems, applications, and practices that are based on them.
An approach that may help identify change areas is to consult design and implementation peer review data ( CMU SEI 1995). Checklists can be used to specifically address the essential properties during these reviews, providing an indication of the sensitivity of the element to changes in the property (e.g., how often HS program business rules change and the impact and time to make those changes).

Top

Roles and Responsibilities

The key roles and their responsibilities are as follows:

Technical Architecture Team. Senior members of the Core Team or individuals with experience in the operational characteristics of the existing systems define the properties. They experience should enable them to establish practical values for the properties based on realistic operational needs and what is reasonable to expect from vendors and the HS Agency system development process.

Top

Artifacts

The following information is used or produced by these activities. Templates, examples, and checklists for identifying and documenting items are available through the Additional Resources section at the end of this page.

A-TARS. The previous version of the A-TARS (if it exists) is used to determine the scope of the changes for an iteration of these activities. The following key part is used:
- Agency-Wide System Properties. These descriptions are the main product of these activities, updating the previous version if it exists. The properties can be documented in the main body of the A-TARS.
Strategic Analysis and Data. The strategic direction, specifically the decisions to keep, replace, renovate, or build on existing IT assets, guides the choice of what practices to integrate into the guidelines and those to omit as legacy systems are retired.
Changes. Changes provided to these activities represent those things in the current A-TARS descriptions that must change. Changes for other parts of the A-TARS also can be generated.
Technical Architecture Work Plans and Direction. These work plans guide the execution of these activities, coordinating the individuals performing these activities with other Technical Architecture tasks and the IT projects.
AIS Design and Implementation Info. An understanding of the existing system characteristics helps to establish practical values. An analysis of the current inventory from the Analyze the Situation activities also helps.
Status. Progress and issues in developing the properties are forwarded to the management activities to ensure coordination between these activities and other Technical Architecture and IT project activities.

Top

Additional Resources

Items that can be used to perform these and other activities are consolidated in the Resources portion of the IT Planning and Management Guides. Resources specific to this activity are cataloged below.

Consolidated Guidance: Establishing Global System Properties
Provides some initial guidance on establishing the properties and design issues. 7-25-01

Top